1. Field of the Invention
This invention is directed to a new method of preparing 2,2-dimethyl-3-((oxyimino)methyl)cyclopropanecarboxylic acids.
2. Description of the Prior Art
U.S. Pat. No. 3,922,269 discloses the preparation of alkyl esters of 2,2-dimethyl-3-((oxyimino)methyl)-cyclopropanecarboxylic acids by treating an alkyl ester of caronaldehydic acid with an equimolar amount of (an acid addition salt of) hydroxylamine or an alkoxylamine of the formula R.sup.1 ONH.sub.2 wherein R.sup.1 is hydrogen, alkyl or alkenyl in a polar solvent. When it is desired that R.sup.1 in the resulting oxime product represent a larger alkyl or alkenyl group than methyl, the patent teaches a two-step process in which one reactant is (an acid addition salt of) hydroxylamine and the resulting oxime is alkylated, as with an alkyl halide in the presence of a hydrogen halide acceptor.
The resulting alkyl esters of 2,2-dimethyl-3-((oxyimino)-methyl)cyclopropanecarboxylic acid are converted under acidic conditions to the free acid and preferably then to the corresponding acid halide for esterification with the desired alcohol or reactive derivative thereof to form the pyrethroid ester pesticides described in the above-noted U.S. patent.